Mxene surface-modified with catechol-containing polymer, mxene conductive material, and surface-modified mxene conductive material

Abstract

The present invention relates to an organic MXene surface-modified with a catechol-containing polymer, a MXene conductive material, and an organic MXene conductive material, and, more specifically, to: a two-dimensional MXene surface-modified with a catechol-containing polymer, the MXene comprising a two-dimensional MXene and a catechol-containing polymer for surface-modifying the two-dimensional MXene particles, thereby being stable in dispersion of various solvents; and a MXene conductive material included in a capacitor or a secondary battery, containing the two-dimensional MXene.

Description

Catechol-containing polymer surface-modified MXene, MXene conductive agent and surface-modified MXene conductive agent

[0001] The present invention relates to a catechol-containing polymer surface-modified maxene, a maxene conductive material, and a surface-modified maxene conductive material.

[0002] Conventional metal materials such as copper and silver have high electrical conductivity and have been used in various ways as electrodes and wiring in electronic devices in the semiconductor, display, and information and communication fields. However, their use is limited due to reasons such as relatively high density, high manufacturing cost, difficulty in applying printing process, oxidation and corrosiveness, and insufficient flexibility.

[0003] MXene is a novel nanomaterial with a two-dimensional structure that has high electrical conductivity and excellent solvent dispersibility (mainly in water and hydrophilic solvents). Therefore, research on the development of MXene and MXene / polymer composite materials is very active in the fields of flexible electrodes for printed electronics, thin-film sensors, high-power batteries and supercapacitors, and electromagnetic shielding.

[0004] MXenes are two-dimensional crystalline transition metal carbides. Twenty different MXene compositions have been synthesized so far, including Ti2C, Ti3C2, Nb2C, V2C, Ta4C3, Mo2TiC2, Mo2Ti2C3, and Cr2TiC2. These MXenes exhibit the best electrical conductivity among the recently developed two-dimensional materials.

[0005] MXene can be synthesized from a ceramic material commonly referred to as MAX. MAX has a layered structure of transition metals [e.g., titanium (Ti), niobium (Nb), vanadium (V), tantalum (Ta), molybdenum (Mo), chromium (Cr)], carbon, and Group 14 elements [e.g., aluminum (Al) or silicon (Si)]. By selectively removing only the Group 14 elements through an etching process, a two-dimensional MXene is obtained.

[0006] In most cases up to now, the etching process has been carried out using a strong acid in an aqueous medium, which causes the surface of MXene to have terminal groups such as -OH, =O, -F, and -Cl, and among these, the -OH functional group in particular gives MXene hydrophilic properties.

[0007] MXene synthesized in this way has excellent water dispersibility properties and can be made into a film or sheet using processes such as filtering or bar coating to exhibit excellent electrical conductivity properties.

[0008] However, the existing aqueous etching process using an aqueous solution cannot avoid the problem that water and dissolved oxygen easily oxidize the surface of MXene during the process, causing the formation of metal oxides such as TiO2, and thus reducing the inherent high electrical conductivity of MXene.

[0009] In addition, due to the hydrophilic nature of the MXene surface, MXene, which can only be dispersed in water, has low interaction and bonding strength with other hydrophobic organic materials (polymers, organic substances), so it has been used very restrictively in forming a uniform composite material. In addition, because a long drying process is required at high temperatures to remove water with a high boiling point and heat of vaporization after the solution process, its application to liquid printing processes such as spray coating, spin coating, inkjet printing, bar coating, gravure coating, and web coating has also been limited.

[0010] Accordingly, the present invention has been devised to solve the above-described conventional problems, and according to an embodiment of the present invention, by chemically modifying the surface of a two-dimensional MXene with a catechol-containing polymer, the problems of the MXene particles are improved, and the MXene particles are manufactured to be easily dispersed in various ways, thereby improving oxidation stability and having excellent solution processability and coatability.

[0011] According to an embodiment of the present invention, a method for manufacturing MXene ink dispersed in various solvents, which can be applied to various fields such as energy storage materials, flexible electrodes, sensor materials, and electromagnetic shielding due to excellent coating properties and electrical conductivity, is provided.

[0012] According to an embodiment of the present invention, the purpose is to provide a maxine conductive material included in a battery or a supercapacitor.

[0013] And, according to an embodiment of the present invention, the purpose is to provide a maxine conductive material that can significantly lower the R value before and after a cycle, significantly increase the discharge capacity, realize a stable capacity retention rate at a high C-rate, and significantly reduce the capacity decline rate at a high C (4C) and long cycle (1000 cyc).

[0014] Meanwhile, the technical tasks to be achieved in the present invention are not limited to the technical tasks mentioned above, and other technical tasks not mentioned can be clearly understood by a person having ordinary knowledge in the technical field to which the present invention belongs from the description below.

[0015] The first object of the present invention can be achieved by providing a two-dimensional MXene; and a catechol-containing polymer for surface-modifying the two-dimensional MXene particles; a two-dimensional MXene surface-modified with a catechol-containing polymer, which is stable in dispersion in various solvents.

[0016] In addition, the catechol-containing polymer may be characterized by including at least one of the following chemical formulas 1 to 5.

[0017] [Chemical Formula 1] PCA (Polycatechol)

[0018]

[0019] [Chemical Formula 2] PCA-PCR (Poly(catechol / p-cresol))

[0020]

[0021] [Chemical Formula 3] PVA-CA (Poly(vinyl alcohol)-catechol)

[0022]

[0023] [Chemical Formula 4] CMC-DA (Carboxymethyl cellulose-dopamine)

[0024]

[0025] [Chemical Formula 5] PVP-CA (Polyvinylpyrrolidone-catechol)

[0026]

[0027] The second object of the present invention can be achieved by providing a conductive material for use in a capacitor or a secondary battery, the conductive material containing a two-dimensional MXene.

[0028] And the above two-dimensional MXene is included as an anode conductive material or a cathode conductive material, and the above two-dimensional MXene is M n+1 X n Crystal cells having an empirical formula of at least one layer comprising a two-dimensional array, wherein X is located within an octahedral array composed of M, wherein M is a metal selected from the group consisting of a Group IIIB metal, a Group IVB metal, a Group VB metal, and a Group VIB metal, and wherein X is C, N, or a combination thereof, and n=1,2,3, or 4.

[0029] In addition, the above two-dimensional MXene is M'2M" n X n+1 Crystal cells having an empirical formula of at least one layer comprising a two-dimensional array, wherein X is located within an octahedral array composed of M, wherein M' and M" are different metals selected from the group consisting of a Group IIIB metal, a Group IVB metal, a Group VB metal, and a Group VIB metal, and wherein X is C, N, or a combination thereof, and n=1 or 2.

[0030] And the above two-dimensional maxine can be characterized as a surface-modified maxine.

[0031] In addition, the surface-modified maxine may be surface-modified through the catechol-containing polymer, and the catechol-containing polymer may be characterized by including at least one of the following chemical formulas 1 to 5.

[0032] [Chemical Formula 1] PCA (Polycatechol)

[0033]

[0034] [Chemical Formula 2] PCA-PCR (Poly(catechol / p-cresol))

[0035]

[0036] [Chemical Formula 3] PVA-CA (Poly(vinyl alcohol)-catechol)

[0037]

[0038] [Chemical Formula 4] CMC-DA (Carboxymethyl cellulose-dopamine)

[0039]

[0040] [Chemical Formula 5] PVP-CA (Polyvinylpyrrolidone-catechol)

[0041]

[0042] And the surface-modified MXene is the organic MXene, and the organic MXene is modified with an external surface of the two-dimensional MXene by one selected from the group consisting of a compound containing a hydroxyl group, an ionic compound, an azide-based surface-modifying compound, a phosphate having a saturated or unsaturated hydrocarbon, and a combination thereof, and the compound containing a hydroxyl group is at least one of a catechol derivative, a diol-based compound, a boronic acid-based compound, a carboxylic acid-based compound, a sulfonic acid-based compound, and a sulfinic acid-based compound, and the ionic compound is a cation selected from the group consisting of an imidazolium-based compound, a pyridinium-based compound, an ammonium-based compound, a phosphinium-based compound, and a combination thereof; and F - , Cl - , Br - , I - , BF 4- , PF 6- , (CF3SO2)2N- , CF3SO3 - , C2N 3- , CH3SO 3- , CF3BF 3- , C2F5BF 3- , NO 3- , CF3CO 2- , C3H5O 3- and may be characterized by including one anion selected from a combination thereof.

[0043] In addition, the phosphate having the above saturated or unsaturated hydrocarbon may be characterized by the following chemical formula 8.

[0044] [Chemical Formula 8]

[0045]

[0046] The above A1, A2 or A3 is a hydrogen atom (-H), a C1-25 saturated or unsaturated hydrocarbon, and is selected from at least one of an amide group (-CONHR), a thioester group (-COSR), and an ester group (-RO-R'-).

[0047] And the above A1, A2 or A3 are each independently C 1-25 Alkyl, C 2-25 Alkenyl, C 2-25 alkynyl, C 6-25 It can be characterized by being selected from aryl, a saturated or unsaturated cyclic or chain hydrocarbon, or containing or not containing 1 to 25 C, N, O or S heteroatoms, or being unsubstituted or substituted with a functional group of hydroxy or carboxyl group, reacting with 0.1 to 50% of the amount of phosphate, adjusting the pH to 2 to 6, and surface-modifying to form an organic protective film, and being stably dispersed in an organic solvent.

[0048] In addition, the above phosphate may be characterized by including at least one of the molecular structure shown in the following chemical formula 9 and 2ethylhexyl phosphate (EHP).

[0049] [Chemical Formula 9]

[0050]

[0051] The third object of the present invention is to manufacture a cathode sludge by mixing a cathode active material, a conductive material, and a binder and coating the cathode sludge on a cathode current collector, and the conductive material can be achieved as a cathode including a MXene conductive material, which is the aforementioned second object MXene conductive material.

[0052] And the above-mentioned positive electrode active material, conductive material, and binder are 75 to 85:5 to 15:5 to 15 wt%, and the conductive material may be characterized by being a mixture of Superfi and Maxine conductive materials, and mixed in a ratio of 4 to 6:4 to 6.

[0053] The fourth object of the present invention is to provide a negative electrode, which is manufactured by mixing a negative electrode active material, a conductive material, and a binder and coating a negative electrode sludge on a negative electrode current collector, wherein the conductive material is a Maxene conductive material of the second object mentioned above, and includes a Maxene conductive material.

[0054] And the above-mentioned positive electrode active material, conductive material, and binder are 75 to 85:5 to 15:5 to 15 wt%, and the conductive material may be characterized by being a mixture of Superfi and Maxine conductive materials, and mixed in a ratio of 4 to 6:4 to 6.

[0055] According to an embodiment of the present invention, by chemically modifying the surface of a two-dimensional MXene with a catechol-containing polymer, problems of the MXene particles are improved, and the MXene particles are manufactured to be easily dispersed in various ways, thereby improving oxidation stability and having excellent solution processability and coatability.

[0056] According to the catechol-containing polymer two-dimensional MXene ink that can be dispersed in various solvents according to an embodiment of the present invention, it has the effect of being applicable to various fields such as energy storage materials, flexible electrodes, anodes, cathodes, conductive materials, sensor materials, and electromagnetic shielding due to its excellent coatability and electrical conductivity.

[0057] According to an embodiment of the present invention, a maxine conductive material included in a battery or a supercapacitor can be provided.

[0058] And according to the Maxene conductive material according to an embodiment of the present invention, it has the effect of being able to significantly lower the R value before and after the cycle, significantly increase the discharge capacity, realize a stable capacity retention rate at a high C-rate, and significantly reduce the capacity decline rate at high C (4C) and long cycles (1000 cyc).

[0059] Meanwhile, the effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0060] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0061] Figure 1 shows the intensity versus 2θ for MAX, MXene, and PCA-OMX.

[0062] Figure 2 is an absorption wavelength graph for PCA-MXene.

[0063] Figure 3 is a Raman Shift-intensity graph for MXene and PCA-OMX.

[0064] Figure 4 is a SEM cross-section of a PCA-MXene film prepared through a membrane filter.

[0065] Figure 5 is an SEM image of PCA-MXene.

[0066] Figure 6 is an absorption wavelength graph of MXene-PCA-PCR (PCA-PCR OMX).

[0067] Figure 7 shows the intensity versus 2θ for MXene, PCA-PCR OMX,

[0068] Figure 8 is a SEM cross-section of a PCA-PCR MXene film prepared through a membrane filter.

[0069] Figure 9 is an SEM image of PCA-PCR-MXene.

[0070] Figure 10 is a contact angle image for a hydrophilic surface.

[0071] Figures 11 and 12 are SEM images of PVA-CA MXene.

[0072] Figure 13 is an absorption wavelength graph of PVA-CA MXene.

[0073] Figure 14 is an image of an MXene sheet,

[0074] Figure 15 is an absorption wavelength graph of CMC-DA MXene.

[0075] Figure 16 shows the intensity versus 2θ for MAX, MXene, and CMC-DA MXene.

[0076] Figure 17 is a SEM cross-section of a CMC-DA-MXene film prepared through a membrane filter.

[0077] Figures 18 and 19 are SEM images of CMC-DA-MXene.

[0078] Figures 23 and 24 show the EIS (Electrochemical Impedance Spectroscopy) results when the existing conductive material, super p, and the conductive material developed in the embodiment of the present invention, PCA-PCR MXene, were used in the NCM anode (Examples 5-1, 5-2, 5-3).

[0079] Figures 25 and 26 show the results of EIS (Electrochemical Impedance Spectroscopy) when the existing conductive material, super p, and the conductive material developed in the example of the present invention, PCA-PCR MXene, were used at the cathode (Examples 6-1, 6-2, 6-3).

[0080] Hereinafter, the composition and manufacturing method of a MXene surface-modified with a catechol-containing polymer according to an embodiment of the present invention, and a MXene conductive material applied to a positive electrode or negative electrode of a capacitor or secondary battery containing the same will be described in detail.

[0081] MXenes are two-dimensional crystalline transition metal carbides. Twenty different MXene compositions have been synthesized so far, including Ti2C, Ti3C2, Nb2C, V2C, Ta4C3, Mo2TiC2, Mo2Ti2C3, and Cr2TiC2. These MXenes exhibit the best electrical conductivity among the recently developed two-dimensional materials.

[0082] MXene can be synthesized from a ceramic material commonly referred to as MAX. MAX has a layered structure of transition metals [e.g., titanium (Ti), niobium (Nb), vanadium (V), tantalum (Ta), molybdenum (Mo), chromium (Cr)], carbon, and Group 14 elements [e.g., aluminum (Al) or silicon (Si)]. By selectively removing only the Group 14 elements through an etching process, a two-dimensional MXene is obtained.

[0083] According to an embodiment of the present invention, the two-dimensional maxine is M, as described in [Background Technology of the Invention]. n+1 X n A two-dimensional array of crystal cells having an empirical formula of at least one layer, wherein each X is positioned within an octahedral array of a plurality of Ms, wherein M is at least one metal selected from the group consisting of a group IIIB metal, a group IVB metal, a group VB metal, and a group VIB metal.

[0084] Each of the above Xs is one selected from C, N and a combination thereof, and n may be 1, 2 or 3.

[0085] According to an embodiment of the present invention, the two-dimensional MXene is M'2M" n X n+1 A two-dimensional array of crystal cells having an empirical formula of at least one layer, wherein each X is positioned within an octahedral array of a plurality of M' and M", wherein the M' and M" are different metals selected from the group consisting of a Group IIIB metal, a Group IVB metal, a Group VB metal, and a Group VIB metal, wherein each X is C, N, or a combination thereof, and wherein n may be 1 or 2.

[0086]

[0087] A positive electrode can be manufactured by dispersing a dispersion of such MXene in a hydrophilic solvent (water) as a conductive material, mixing it with a binder and a positive electrode active material to manufacture a positive electrode slurry, and coating it on aluminum foil, which is a positive electrode current collector. At this time, the positive electrode active material, the MXene conductive material, and the binder can be mixed in a ratio of 75 to 85:5 to 15:5 to 15 wt%.

[0088] In addition, a dispersion of Maxine in a hydrophilic solvent (water) can be used as a Maxine conductive agent, mixed with a binder and a negative electrode active material to produce a negative electrode slurry, and coated on an aluminum copper foil, which is a negative electrode current collector, to produce a negative electrode.

[0089] In an embodiment of the present invention, organic MXenes that have been surface-modified to be hydrophobic, surface-modified to enable dispersion in various solvents, or manufactured using an organic etching method can be combined with and coated on positive electrode active material particles. By applying surface-modified MXenes, resistance can be further reduced, and compared to non-surface-modified MXenes, the bonding strength with positive electrode active materials can be increased, thereby enhancing stability.

[0090] Various embodiments may be applied to the method of surface modification of Maxine, and these embodiments are merely preferred examples and should not be construed as limiting the scope of the rights.

[0091]

[0092] These surface-modified MXenes can be manufactured by surface-modifying two-dimensional MXene particles using catechol-containing polymers to ensure dispersion stability in various solvents.

[0093] In an embodiment of the present invention, the catechol-containing polymer may include at least one of the following chemical formulae 1 to 4.

[0094] [Chemical Formula 1] PCA (Polycatechol)

[0095]

[0096] [Chemical Formula 2] PCA-PCR (Poly(catechol / p-cresol))

[0097]

[0098] [Chemical Formula 3] PVA-CA (Poly(vinyl alcohol)-catechol)

[0099]

[0100] [Chemical Formula 4] CMC-DA (Carboxymethyl cellulose-dopamine)

[0101]

[0102] [Chemical Formula 5] PVP-CA (Polyvinylpyrrolidone-catechol)

[0103]

[0104]

[0105] In addition, the organic MXene can modify the outer surface of the two-dimensional MXene with one selected from the group consisting of a compound containing a hydroxyl group, an ionic compound, an azide-based surface-modifying compound, a phosphate having a saturated or unsaturated hydrocarbon, and a combination thereof.

[0106] The compound containing a hydroxyl group may be one selected from the group consisting of catechol derivatives, diol compounds, boronic acid compounds, carboxylic acid compounds, sulfonic acid compounds, sulfinic acid compounds, compounds of the following chemical formula 5, and combinations thereof.

[0107] [Chemical Formula 6]

[0108]

[0109] By selecting a compound containing the hydroxyl group from the above, the solubility of the compound in an organic solvent can be changed, and the binding force to the surface of the two-dimensional MXene can be improved.

[0110] And the ionic compound is a cation selected from the group consisting of imidazolium compounds, pyridinium compounds, ammonium compounds, phosphinium compounds and combinations thereof; and F - , Cl - , Br - , I - , BF 4- , PF 6- , (CF3SO2)2N - , CF3SO3- , C2N 3- , CH3SO 3- , CF3BF 3- , C2F5BF 3- , NO 3- , CF3CO 2- , C3H5O 3- and may include one anion selected from a combination thereof.

[0111] And the catechol derivative can be represented by the following chemical formula.

[0112]

[0113] Here, X is selected from at least one of a hydrogen atom (-H), an ester group (-COOR), an amide group (-CONHR), a thioester group (-COSR), a hydrocarbon group (-R), and an ether group (-RO-R'-), and R and R' are each independently selected from a C1-25 aliphatic hydrocarbon and an aromatic hydrocarbon.

[0114] The above R and R' are each independently a saturated or unsaturated cyclic or chain hydrocarbon selected from C1-25 alkyl, C2-25 alkenyl, C2-25 alkynyl, C6-25 aryl, or a heteroatom of 1 to 25 C, N, O or S, or may be unsubstituted or substituted with a functional group of hydroxy or carboxyl.

[0115] And the saturated or unsaturated chain hydrocarbon may or may not contain at least one selected from nitrogen, oxygen, sulfur, sulfinyl and sulfonyl in the middle or side chain of the chain.

[0116]

[0117] And the azide-based surface modification compound may be an azide-based compound having the following chemical formulas 7 and 7a.

[0118] [Chemical Formula 7]

[0119]

[0120] [Chemical Formula 7a]

[0121]

[0122] In the above chemical formula 7, Y can be represented by the above chemical formula 7a, in the above chemical formula 7a, R2 is an azide group, R3 is 1 to 4 or more alkyl groups or hydrogen atoms and halogen groups, A1 can be selected from at least one of an ester group (-COOR), an amide group (-CONHR), a thioester group (-COSR), a hydrocarbon group (-R), and an ether group (-RO-R'-), and the R and R' can each be independently selected from a C1-30 aliphatic hydrocarbon and an aromatic hydrocarbon.

[0123] A2 is independently C 1-25 Alkyl, C 2-25 Alkenyl, C 2-25 alkynyl, C 6-25 It may be a saturated or unsaturated chain or cyclic hydrocarbon selected from aryl.

[0124] R1 in the above chemical formula 7 is an atomic bond, substituted or unsubstituted C1 to C 25 Alkyl group, substituted or unsubstituted C4 to C 20 Aryl group, substituted or unsubstituted C5 to C 21 This heteroaryl group and substituted or unsubstituted C1 to C 20 At least one of the alkylamine groups is selected, and n is an integer from 1 to 10.

[0125] The above A2 may be a saturated or unsaturated heterocyclic or chain hydrocarbon each independently containing at least one heteroatom selected from 1 to 25 carbons, nitrogen, oxygen and sulfur, and the saturated or unsaturated heterocyclic or chain hydrocarbon may not contain or contain at least one selected from carbon, nitrogen, oxygen and sulfur in the middle or catalytic portion of each chain.

[0126]

[0127] And the phosphate having a saturated or unsaturated hydrocarbon may be a compound represented by the following chemical formula 8.

[0128] [Chemical Formula 8]

[0129]

[0130] The above A1, A2 or A3 is a hydrogen atom (-H), a C1-25 saturated or unsaturated hydrocarbon, and is selected from at least one of an amide group (-CONHR), a thioester group (-COSR), and an ester group (-RO-R'-).

[0131] The above A1, A2 or A3 are each independently C 1-25 Alkyl, C 2-25 Alkenyl, C 2-25 alkynyl, C 6-25 A saturated or unsaturated ring or chain hydrocarbon selected from aryl, or may be unsubstituted or substituted with a functional group of a hydroxyl group or a carboxyl group, or may not contain or contain 1 to 25 heteroatoms of C, N, O or S.

[0132] A1, A2 or A3 are each independently a saturated or unsaturated cyclic or chain hydrocarbon selected from C1-25 alkyl, C2-25 alkenyl, C2-25 alkynyl, C6-25 aryl, or may be unsubstituted or substituted with a functional group of hydroxy or carboxyl, or may not contain or contain 1 to 25 heteroatoms of C, N, O or S.

[0133] And the amount of the above phosphate is reacted with 0.1 to 50%, the pH is adjusted to 2 to 6, and the surface is modified to form an organic protective film and can be stably dispersed in an organic solvent.

[0134] Additionally, the phosphate may include at least one of the molecular structures shown in the chemical formula below, or 2-ethylhexyl phosphate (EHP).

[0135] [Chemical Formula 9]

[0136]

[0137]

[0138] In addition, as mentioned above, the organic MXene manufactured by modifying the surface of the MXene with various organic ligands can be coated on a metal foil, and the organic MXene manufactured by applying an organic etching method can be coated on a metal foil.

[0139] An organic etching method according to an embodiment of the present invention comprises preparing MAX and then organically etching A of the MAX using an organic etching reagent and an organic solvent (wherein M is a transition metal, A is a group 14 element, and X is carbon or nitrogen).

[0140] The organic etching reagent according to an embodiment of the present invention may be an organic base-hydrogen fluoride addition product.

[0141] And the organic base is an organic base compound, and the organic base compound may be an organic base, an organic base derivative, or an organic base and a polymer bonding compound or mixture that dissolves better in an organic solvent than in water and allows hydrogen fluoride to remain in the organic solvent by stirring or heating.

[0142] Additionally, the organic base-hydrogen fluoride adduct may be at least one of a pyridine-hydrogen fluoride adduct (Olah's Reagent), an N,N-dimethylpropylene urea (DMPU)-hydrogen fluoride adduct (DMPU-HF adduct), and an alc triethylamine (TEA)-hydrogen fluoride adduct (TEA-HF adduct).

[0143] Additionally, the organic base-hydrogen fluoride addition product may be at least one of those represented by the following chemical formula 10.

[0144] [Chemical Formula 10]

[0145]

[0146] And the organic base compound may be at least one of those shown in the chemical formula 11 below.

[0147] [Chemical Formula 11]

[0148]

[0149]

[0150]

[0151] In the above chemical formula 11, x and y are mutually dependent, the sum is 100% and each has a value of 10% to 90%, the range of n is 1 to 100,000, and R, R', and R'' are each independently an aliphatic hydrocarbon and perfluoroalkyl, or an aromatic hydrocarbon and a heterocyclic compound having a length of C1 to C25.

[0152] Below, experimental examples of the present invention and experimental result data will be described.

[0153] Example 1: MXene synthesis (MILD synthesis method)

[0154] 45 mL of HCl, 15 mL of distilled water, and 4.8 g of LiF were added to a Teflon round-bottom flask, and 3 g of MAX(Ti3AlC2) was added. The temperature was raised to 35°C, and the mixture was heated and stirred for 24 hours. The solution was then transferred to a conical tube and centrifuged repeatedly until the pH reached 5 to 6. After centrifugation at 3,500 RPM for 30 minutes, only the supernatant was separated and used.

[0155]

[0156] Example 2: MXene synthesis (MILD-HF synthesis method)

[0157] A Teflon round-bottom flask was added 45 mL of HCl, 15 mL of distilled water, 4.5 mL of HF, and 4.8 g of LiF. 3 g of MAX (Ti3AlC2) was then added, the temperature was raised to 35°C, and the mixture was heated and stirred for 24 hours. The solution was then transferred to a conical tube and centrifuged repeatedly until the pH reached 5–6. After centrifugation at 3,500 RPM for 30 minutes, only the supernatant was separated and used.

[0158]

[0159] Example 3: Synthesis of a catechol-containing polymer surface-modified organic dispersion MXene (PCA-PCR MXene)

[0160] Prepared MXene (Ti3C2T) x ) The aqueous solution was diluted to 1 mg / mL to prepare 35 mL. 3.5 mg of each catechol-containing polymer of the aforementioned chemical formula 1 or chemical formula 2 was dissolved in 10 mL of an organic solvent (ethanol) (DAESUNG) to prepare an organic solution.

[0161] The aqueous solution of MAXINE and the organic solution of the catechol-containing polymer were mixed and stirred at room temperature for 24 hours to perform the reaction. After 24 hours, stirring was stopped, and the MAXINE surface-modified with the catechol-containing polymer was separated using a centrifuge, and then washed 3 to 5 times with the desired organic solvent (NMP) (DAESUNG) to prepare an organic dispersion ink of MAXINE for a conductive material.

[0162]

[0163] Example 4: Synthesis of catechol-containing polymer surface-modified water-dispersed MXene (CMC-DA-MXene)

[0164] Prepared MXene (Ti3C2T) x) The aqueous solution was diluted to 1 mg / mL to prepare 35 mL. The aqueous solution was prepared by dissolving 3.5 mg of each of the catechol-containing polymers of the aforementioned chemical formula 5 or chemical formulas 3 and 4 in 10 mL of distilled water. The aqueous solution of MAXINE and the aqueous solution of the catechol-containing polymer were mixed and stirred at room temperature for 24 hours to perform the reaction.

[0165] After 24 hours, stirring was stopped, and the surface-modified MAXINE with a catechol-containing polymer was separated using a centrifuge, and then washed 3 to 5 times with distilled water to prepare a MAXINE water-dispersed ink for a conductive material.

[0166]

[0167] Example 5: Fabrication of anode and half-cell

[0168] The cathode manufactured for the electrochemical performance test of the MXene conductive material used NCM cathode active material, Super P (common conductive material), PCA-PCR MXene (Example 3, MXene conductive material), and PVDF (Polyvinylidene fluoride) binder.

[0169] The positive electrode active material, conductive agent, and binder were mixed in a weight ratio (wt.%) of 80:10:10, respectively, and mixed in a solvent, NMP (N-methyl-2-pyrrolidone), to prepare a slurry, which was then evenly mixed using a mortar and pestle for several minutes.

[0170] The challenge agent was PCA-PCR MXene prepared at a concentration of 20 mg / mL at 0 wt.% (Example 5-1, 0 mL), 5 wt.% (Example 5-2, 0.25 mL), and 10 wt.% (Example 5-3, 0.5 mL), and NMP was added to adjust the concentration of the slurry.

[0171] The prepared positive electrode slurry was coated on aluminum foil using a 100 μm Dr. Blade, dried in a vacuum oven at 60°C for 5 hours, and then rolled to manufacture a positive electrode.

[0172] To manufacture a coin cell, a negative electrode lithium (Li foil), a separator PE (Polyethylene), and an electrolyte 1 M LiPF6EC:DMC (1:1 v / v) were used. The coin cell type was 2032 type, and the electrode preparation process was performed in a dry room with a negative pressure of 60 degrees and a humidity of <1 ppm.

[0173] Cathode active material (NCM) Conductive material Binder (PVDF) Super PPCA-PCR MXene Example 5 - 180 mg (80 wt.%) 10 mg (10 wt.%) 0 mg (0 wt.%) 10 mg (10 wt.%) Example 5 - 280 mg (80 wt.%) 5 mg (5 wt.%) 5 mg (5 wt.%) 10 mg (10 wt.%) Example 5 - 380 mg (80 wt.%) 0 mg (0 wt.%) 10 mg (10 wt.%) 10 mg (10 wt.%)

[0174] Example 6: Fabrication of cathode and half-cell

[0175] The negative electrode manufactured for the electrochemical performance test of the Maxene challenger used a mixed negative electrode active material of Hollow silicon (H-Si, particle size: 200 nm) and Graphite, Super P, CMC-MXene (Example 4), and CMC (Carboxymethyl cellulose) binder.

[0176] The negative active material, conductive agent, and binder were mixed in a weight ratio (wt.%) of 80:10:10, respectively, and mixed in distilled water as a solvent to prepare a slurry, which was then evenly mixed using a mortar and pestle for several minutes. The negative active material was a mixture of H-Si and graphite in a mass ratio (wt.%) of 5:75, and the conductive agent was CMC-MXene prepared at a concentration of 20 mg / mL, which was used at 0 wt.% (Example 6-1, 0 mL), 5 wt.% (Example 6-2, 0.25 mL), and 10 wt.% (Example 6-3, 0.5 mL), and the concentration of the slurry was adjusted by adding distilled water.

[0177] The prepared cathode slurry was coated on copper foil using a 100 μm Dr. Blade, dried in a vacuum oven at 60°C for 5 hours, and then rolled to manufacture a cathode.

[0178] To manufacture a coin cell, anode lithium (Li foil), separator PE (Polyethylene), and electrolyte 1 M LiPF6EC:DMC (1:1 v / v) were used. The coin cell type was 2032 type, and the electrode preparation process was performed in a dry room with a negative pressure of 60 degrees and a humidity of <1 ppm.

[0179] ClassificationCathode active material(H-Si / Graphite)Conductive materialBinder(CMC)Super PCMC-DA-MXeneExample 6-15 mg / 75 mg(80 wt.%)10 mg(10 wt.%)0 mg(0 wt.%)10 mg(10 wt.%)Example 6-25 mg / 75 mg(80 wt.%)5 mg(5 wt.%)5 mg(5 wt.%)10 mg(10 wt.%)Example 6-35 mg / 75 mg(80 wt.%)0 mg(0 wt.%)10 mg(10 wt.%)10 mg(10 wt.%)

[0180] Figure 1 shows the intensity versus 2θ for MAX, MXene, and PCA-OMX. As shown in Figure 1, the sharp (002) peak observed at 9.45° for the Ti3AlC2MAX phase shifted to a lower angle. After removing the Al layer, Ti3AlC2 became Ti3C2T. x When converted to MXene, it shifted to 7.14°. In addition, PCA-MXene shifted to a lower angle of 6.84° of (002) than MXene, and PCA was attached to the MXene surface to form Ti3C2T x This result indicates that the interlayer spacing between nanosheets has increased.

[0181] Figure 2 illustrates an absorption wavelength graph for PCA-MXene. As shown in Figure 2, PCA-MXene dispersed in ethanol showed no change in UV-vis absorption wavelength for over a month. This indicates that MXene exhibits excellent stability because PCA prevents gradual oxidation to TiO2.

[0182] Figure 3 shows Raman shift-intensity graphs for MXene and PCA-OMX. As shown in Figure 3, MXene and PCA-MXene have Raman shift-intensity peaks at 204.5, 391.6, and 580 cm -1 It can be seen that the characteristic Raman peaks of MXene were observed in PCA-MXene. In addition, the peaks at 1348.6 and 1579.5 cm corresponding to the D and G bands, respectively. -1 It exhibited two distinct Raman peaks, which confirmed the PCA fixed on the MXene surface.

[0183] Figure 4 illustrates an SEM cross-section of a PCA-MXene film prepared through a membrane filter. As shown in Figure 4, the presence of PCA between the MXene layers allows for a well-aligned stacking by bonding them together, thereby avoiding the formation of internal voids seen in the original MXene film.

[0184] Figure 5 is an SEM image of PCA-MXene. As shown in Figure 5, unlike the smooth and clean surface observed in MXene, PCA-MXene has very small PCA particles uniformly distributed on the surface and edges, which shows that PCA has been successfully immobilized on MXene.

[0185]

[0186] Figure 6 illustrates an absorption wavelength graph of MXene-PCA-PCR (PCA-PCR OMX). As shown in Figure 6, when PCA-PCR was surface-modified on the MXene surface and oxidation occurred over time, it was measured by UV-Vis, and it was confirmed that there was no difference between 1 day and 7 days.

[0187] Figure 7 shows the intensity versus 2θ for MXene and PCA-PCR OMX. As shown in Figure 7, the (002) peak of PCA-PCR MXene shifted to a lower angle of 6.64° than that of MXene at 7.31°, indicating that PCA-PCR was attached to the MXene surface, increasing the interlayer spacing between Ti3C2Tx nanosheets.

[0188] As shown in Fig. 8, the SEM cross-section of the PCA-PCR MXene film prepared through the membrane filter shows that the PCA-PCR is present between the MXene layers, allowing them to bond to each other and form a well-aligned stack, thus avoiding the formation of internal voids seen in the original MXene film.

[0189] Figure 9 is a SEM image of PCA-PCR-MXene. As shown in Figure 9, unlike the smooth and clean surface observed in MXene, PCA-PCR-MXene shows that very small PCA-PCR particles are uniformly distributed on the surface and edges, indicating that PCA-PCR was successfully immobilized on MXene.

[0190] Figure 10 is a contact angle image for a hydrophilic surface. As shown in Figure 10, the contact angle is low due to the hydrophilic surface of MXene, but the surface-modified PCA-PCR MXene is hydrophobic, so it can be seen that the contact angle shows a higher value.

[0191]

[0192] Figures 11 and 12 are SEM images of PVA-CA MXene. As shown in Figure 11, when PVA-CA MXene is viewed using an AAO film, a transparent thin film that can be seen all the way to the back of the film can be observed.

[0193] And as shown in Fig. 12, unlike the smooth and clean surface observed in MXene, PVA-CA MXene has a consistent surface and hexagonal arrangement, showing that PVA-CA was successfully fixed to MXene.

[0194] Figure 13 illustrates an absorption wavelength graph of PVA-CA MXene. As shown in Figure 13, the surface-modified PVA-CA MXene is dispersed in an organic solvent, and even after one month, the peaks at 300 to 350 nm and the peaks at 750 to 800 nm do not decrease significantly, confirming that oxidation has not progressed significantly. This indicates that PVA-CA MXene has excellent oxidation stability.

[0195] Additionally, as shown in Fig. 14, it can be confirmed that one sheet of MXene is about 2.5 um, and the height of the MXene sheet is about 2.2 nm.

[0196]

[0197] Figure 15 illustrates an absorption wavelength graph of CMC-DA MXene. As shown in Figure 15, the y-values ​​of the unique peaks of MXene decrease after 10 days, confirming that oxidation has occurred. This indicates that surface modification through CMC does not significantly affect the oxidation stability of MXene.

[0198] Figure 16 shows the intensity versus 2θ for MAX, MXene, and CMC-DA MXene. As shown in Figure 16, the (104) peak unique to MAX disappears in MXene and CMC-DA-MXene, confirming that etching was successful. The (002) peak of MXene and CMC-DA-MXene appears at a lower angle than the (002) peak of MAX, confirming that d-spacing has increased.

[0199]

[0200] As shown in Fig. 17, the SEM cross-section of the CMC-DA-MXene film prepared through the membrane filter shows that the CMC is present between the MXene layers, which allows them to bond with each other and form a well-aligned stack, thus avoiding the formation of internal voids seen in the original MXene film.

[0201] And as shown in Fig. 18, the edges of the CMC-DA-MXene sheet are clean, confirming that oxidation of MXene hardly occurs. It can be confirmed through SAED that the structure of MXene is maintained even after surface modification of CMC.

[0202] Additionally, as shown in Fig. 19, it can be confirmed that the width of the CMC-DA-MXene sheet is about 1.5 um and the height is about 2.8 nm.

[0203]

[0204] As shown in Fig. 20, to determine the oxidation stability, each sample group was left for one week after synthesis, and the oxidation degree of each sample was measured through UV-Vis analysis. As a result, it was confirmed that the untreated MXene solution was oxidized, but the PVP-CA modified MXene maintained its own peak, confirming that oxidation stability could be provided.

[0205] And as shown in Fig. 21, in order to confirm the degree of surface modification by d-spacing, XRD analysis was performed on each sample group after film production under the same environment. Compared to the existing MXene, it was confirmed that the (002) 2θ value tended to decrease as the Catechol content increased, which means that d-spacing gradually increased according to the Catechol content.

[0206]

[0207] Figure 23 shows the results of EIS (Electrochemical Impedance Spectroscopy) when the existing conductive material, super p, and the conductive material, PCA-PCR MXene, developed in the examples of the present invention, were used on the NCM anode (Examples 5-1, 5-2, and 5-3).

[0208] As shown in Fig. 23, the EIS (Electrochemical Impedance Spectroscopy) results when the existing conductive material, super p, and the conductive material developed in this study, PCA-PCR MXene, were used on the NCM cathode showed that the MXene conductive material showed a lower EIS value than the existing conductive material, and the result of mixing them in a ratio of 5:5 showed a lower value than when the two conductive materials were used alone.

[0209] Also, as shown in Fig. 24, as the ratio of PCA-PCR MXene increases in the SEM image, spherical Super P is not observed, and it can be observed that the two-dimensional particles of MXene are well covered. It is shown that the ratio of Ti increases compared to Ni, Co, and Mn as the ratio of PCA-PCR MXene increases.

[0210]

[0211] Figure 25 shows the EIS (Electrochemical Impedance Spectroscopy) results when the existing conductive material, super p, and the conductive material developed in the examples of the present invention, CMC-DA MXene, were used on the Si / graphite cathode (Examples 6-1, 6-2, and 6-3). As shown in Figure 25, the MXene conductive material showed a lower EIS value than the existing conductive material, and the result of mixing them in a 5:5 ratio showed a lower value than when the two conductive materials were used alone.

[0212] And as shown in Fig. 26, it can be observed in the SEM image that as the ratio of CMC-DA MXene increases, the two-dimensional particles, MXene, cover well. It shows that as the ratio of CMC-DA MXene increases, the ratio of Ti to Si increases.

[0213]

[0214] In addition, the devices and methods described above are not limited to the configurations and methods of the embodiments described above, and the embodiments may be configured by selectively combining all or part of each embodiment so that various modifications can be made.

Claims

1. 2-dimensional maxine; and Including a catechol-containing polymer for surface modification of the above two-dimensional maxine particles; Two-dimensional maxene surface-modified with catechol-containing polymers that is stable in various solvent dispersions.

2. In paragraph 1, A two-dimensional maxine surface-modified with a catechol-containing polymer, wherein the catechol-containing polymer comprises at least one of the following chemical formulas 1 to 4. [Chemical Formula 1] PCA (Polycatechol) [Chemical Formula 2] PCA-PCR (Poly(catechol / p-cresol)) [Chemical Formula 3] PVA-CA (Poly(vinyl alcohol)-catechol) [Chemical Formula 4] CMC-DA (Carboxymethyl cellulose-dopamine) [Chemical Formula 5] PVP-CA (Polyvinylpyrrolidone-catechol) 3. As a conductive material included in a capacitor or secondary battery, Maxine challenger containing two-dimensional maxine.

4. In paragraph 3, The above two-dimensional maxine is included as an anode conductive material or a cathode conductive material, The above two-dimensional MXene is M n+1 X n Crystal cells having an empirical formula of at least one layer forming a two-dimensional array, wherein X is located within an octahedral array composed of M, A MXene conductive agent, wherein M is a metal selected from the group consisting of a group IIIB metal, a group IVB metal, a group VB metal, and a group VIB metal, and X is C, N, or a combination thereof, and n=1,2,3, or 4.

5. In paragraph 4, The above two-dimensional MXene is M'2M" n X n+1 Crystal cells having an empirical formula of at least one layer forming a two-dimensional array, wherein X is located within an octahedral array composed of M, The above M' and M" are different metals selected from the group consisting of Group IIIB metals, Group IVB metals, Group VB metals, and Group VIB metals, The above X is C, N or a combination thereof, and n=1 or 2, a maxine challenge agent.

6. In paragraph 4, The above two-dimensional maxine is a surface-modified maxine, a maxine challenge agent.

7. In paragraph 6, The surface-modified maxine is surface-modified through the catechol-containing polymer, The catechol-containing polymer is a maxine challenge agent comprising at least one of the following chemical formulas 1 to 5: [Chemical Formula 1] PCA (Polycatechol) [Chemical Formula 2] PCA-PCR (Poly(catechol / p-cresol)) [Chemical Formula 3] PVA-CA (Poly(vinyl alcohol)-catechol) [Chemical Formula 4] CMC-DA (Carboxymethyl cellulose-dopamine) . [Chemical Formula 5] PVP-CA (Polyvinylpyrrolidone-catechol) 8. In paragraph 7, The above surface-modified MXene is the above organic MXene, The above organic MXene is modified on the outer surface of the two-dimensional MXene with one selected from the group consisting of a compound containing a hydroxyl group, an ionic compound, an azide-based surface-modifying compound, a phosphate having a saturated or unsaturated hydrocarbon, and a combination thereof. The compound containing the above hydroxyl group is at least one of a catechol derivative, a diol compound, a boronic acid compound, a carboxylic acid compound, a sulfonic acid compound, and a sulfinic acid compound. The above ionic compound is a cation selected from the group consisting of imidazolium compounds, pyridinium compounds, ammonium compounds, phosphinium compounds, and combinations thereof; and F - , Cl - , Br - , I - , BF 4- , PF 6- , (CF3SO2)2N - , CF3SO3 - , C2N 3- , CH3SO 3- , CF3BF 3- , C2F5BF 3- , NO 3- , CF3CO 2- , C3H5O 3- A maxine challenge agent comprising an anion selected from a combination thereof.

9. In paragraph 8, The phosphate having the above saturated or unsaturated hydrocarbon is a MXene challenge agent represented by the following chemical formula 8: [Chemical Formula 8] The above A1, A2 or A3 is a hydrogen atom (-H), a C1-25 saturated or unsaturated hydrocarbon, It is selected from at least one of an amide group (-CONHR), a thioester group (-COSR), and an ester group (-RO-R'-).

10. In paragraph 9, The above A1, A2 or A3 are each independently C 1-25 Alkyl, C 2-25 Alkenyl, C 2-25 alkynyl, C 6-25 A saturated or unsaturated ring or chain hydrocarbon selected from aryl, or containing or not containing 1 to 25 heteroatoms of C, N, O or S, or unsubstituted or substituted with a functional group of hydroxy or carboxyl group, An active material combined with MXene, which is reacted with 0.1 to 50% of the above-mentioned phosphate, adjusted to pH 2 to 6, and surface-modified to form an organic protective film and is stably dispersed in an organic solvent.

11. In paragraph 10, The above phosphate is a MXene challenge agent comprising at least one of the molecular structures represented by the following chemical formula 9 and 2ethylhexyl phosphate (EHP): [Chemical Formula 9] 12. As a polarity, It is manufactured by coating a cathode sludge mixed with cathode active material, conductive material, and binder on a cathode current collector. The above-mentioned conductive material is a cathode including a maxine conductive material, which is a maxine conductive material of claims 3 to 10.

13. In paragraph 12, The above cathode active material, conductive material, and binder are 75 to 85: 5 to 15: 5 to 15 weight %, The above-mentioned conductive material is a positive electrode including a Maxene conductive material, which is a mixture of Superfi and Maxene conductive material, and is mixed in a ratio of 4 to 6:4 to 6.

14. As a cathode, It is manufactured by mixing negative electrode active material, conductive material, and binder and coating the negative electrode sludge on the negative electrode current collector. The above-mentioned conductive material is a cathode including a Maxene conductive material, which is a Maxene conductive material of claims 3 to 10.

15. In paragraph 14, The above cathode active material, conductive material, and binder are 75 to 85: 5 to 15: 5 to 15 weight %, The above-mentioned conductive material is a cathode including a Maxene conductive material, which is a mixture of Superfi and Maxene conductive material, and is mixed in a ratio of 4 to 6:4 to 6.

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